This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Experiments were carried out to try to functionalize single-walled carbon nanotubes using photochemically generated hydroxyl radicals. Electron paramagnetic resonance (EPR) spectroscopy was used as a tool to help confirm that hydroxyl radicals were indeed being produced in the reaction mixture. To do this, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), a well-known spin trap, was used to scavenge radicals in solution. The EPR spectrum allowed us to identify alcohol contaminants in our solution and led to cleaner experimental conditions where hydroxyl radicals were successfully trapped. Without the EPR experiment, we would have not been able to identify specific contaminants that were interfering with our experiment. EPR was also the best way to positively confirm the production of hydroxyl radicals with our experimental conditions.